The proposed R25 Summer Intern Program (SIP) in Environmental Health Sciences seeks to offer summer research training in environmental health sciences for 10 outstanding under-represented minority undergraduate students from across the nation. These interns will participate in the investigators well-established and comprehensive 9-week laboratory training program at Harvard School of Public Health in conjunction with its Ph.D. Program in Biological Sciences in Public Health. HSPH has pledged to match NIH support to enhance the experience offered by its nationally recognized summer internship. The investigators will provide hands-on training in bench research, develop lasting mentoring relationships between summer undergraduate interns and ten outstanding HSPH faculty, and promote interest in environmental health graduate science careers by organizing curricular and extracurricular activities for interns enrolled in their program. All training program faculty are experienced in serving as mentors for minority students and have worked with their summer program for several years. Additionally, these faculty members have active research programs in a broad spectrum of research areas, including environmental health, genetics, molecular epidemiology and biomarkers, toxicology, and mechanistic disease research. This breadth of interest will benefit their program as each of the faculty will speak to the students about their research and professional development to foster careers in environmental sciences. Prospective applicants from across the nation will be evaluated for their potential based on statement of purpose, coursework and grades at the undergraduate level, and letters of reference. Those accepted into the program will begin their summer experience the second or third week in June. The SIP includes an individualized supervised research project in HSPH faculty laboratories, laboratory safety training, responsible conduct of science, participation in a weekly seminar series focusing on environmental health sciences, formal and informal mentoring lunches with HSPH faculty and graduate students, university-wide lectures bringing together summer interns across the university, afternoon and evening socials, practical preparation for the graduate school admission process, and Harvard University-sponsored Science Symposium for trainees to present the results of their research. The program evaluation will assess how well the SIP enhanced the motivation and academic preparation and participation in environmental health careers. The specific aim is to motivate and enhance the pipeline of underrepresented minority students seeking graduate level training in the environmental health sciences.